Various fields such as, for example, biotechnology, semiconductor, pharmaceutical, food processing, and medical, require fluid handling systems that are clean and sterile while at the same time having increased cycle life and operating pressure. A very important consideration is ease with which the fluid handling components can be cleaned. The ease with which a system can be cleaned depends on, among other things, minimal dead volumes and entrapment areas. The fluid handling system must also use components that are inert to the fluid. Such systems often use valves as flow control devices, and diaphragm valves in particular are often used.
U.S. Pat. No. 5,549,134 (the "'134 patent" hereinafter), the entire disclosure of which is fully incorporated herein by reference, describes a diaphragm valve design that is particularly well suited for these various sanitary applications. The present invention is directed to various improvements and additional features in the design of the '134 patent valve to enhance its cleanability and operating performance including, among other things, its operating pressure characteristic and cycle life.